Here’s how the Daily Prophet looks:

As seen above, the Daily Prophet’s images are magical, with their subjects moving around on the page — more like video than a traditional photograph. The engineering team drew inspiration from this. “News Feed should clearly be alive and move in your hands on smartphones,” Cox told Fortune — and Daily Prophet-style autoplay was the obvious way to achieve this.

In December 2013, autoplay was added — and views skyrocketed, transforming Facebook into the video behemoth it is today. Elsewhere in the Fortune story it’s revealed that Facebook enjoyed 10 billion views of “Ice Bucket Challenge” videos — that’s 10 times as many as on YouTube.